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Improvement of Spatial Resolution by Selfconsistent Full Muon Track Reconstruction in Gaseous Detectors

B. Flierl, O. Biebel, M. Herrmann, R. Hertenberger, F. Klitzner, P. Loesel, R. Mueller, A. Zibell

in 38th International Conference on High Energy Physics

Contribution: pdf


Full track reconstruction for charged particles in thin gaseous detectors can be achieved using a Time-Projection-Chamber like (TPC) read-out and analysis method. This method has proven to be very successfull for thermal neutron detection in gaseous electron multiplier (GEM) detectors\cite{Sauli}, based on the full track reconstruction of the charged Helium and Lithium ions produced in a thin $^{10}$B conversion layer building the cathode of the triple GEM detector. An improvement from FWHM 3.4 mm to 0.25 mm of the spatial resolution of the interaction point of the neutron in the $^{10}$B layer has been observed using an Ar-CO2 gas mixture as detector gas. For the achievable track resolution the drift velocity and thus the composition of the drift gas is of big importance. A self-consistent algorithm allows for optimized results without the development of gas-parameters, as otherwise usual, in prior test experiments with well known angle of incidence of the ions. Simulations predict, that by application of this method the spatial resolution for minimal ionizing particles can be improved as well. For verification a compact cosmic muon telescope has been commissioned, which consists of four triple GEM detectors with two-dimensional strip read-out of 0.4 mm pitch in x and y. All strips are read out by APV25 frontend boards. Muon tracks are reconstructed using the TPC-like method in one of the detectors and are then compared to the predicted track from the other three detectors defined by the center of charge position in every detector.